Calcium antagonists and the kidney. Implications for renal protection.

During the past decade, attention has been focused on the effects of calcium antagonists on renal function. When administered in vitro to the isolated perfused kidney (IPK), calcium antagonists exhibit consistent actions, permitting characterization of their renal effects. Calcium antagonists do not affect the vasodilated IPK, but do dramatically alter the hemodynamic response of the kidney to vasoconstrictor agents. Our recent studies using the isolated perfused hydronephrotic rat kidney model, which permits direct visualization of afferent and efferent arterioles, demonstrate that the preferential augmentation of glomerular filtration rate (GFR) observed in the IPK is attributable to preferential vasodilation of preglomerular vessels. Although the clinical implications of such observations have not been fully delineated, recent studies indicate that calcium antagonists exert salutary effects on renal function in clinical settings, characterized by impaired renal hemodynamics such as radiocontrast-induced nephrotoxicity and transplant-associated acute renal insufficiency. It is apparent, however, that the salutary effects of calcium antagonists on renal hemodynamics recommend their use in the management of essential hypertension.